There have been conflicting reports regarding the depth at which the miners were trapped. The National Mining and Metal Workers Union (SNTMMSRM) stated that the trapped miners were approximately 1,600 feet below ground, via a mile-long horizontal shaft. Grupo México released a statement saying that the miners were about 500 feet below ground when the explosion occurred. Guadalupe Rosales Martínez, the sister of a worker saved from the mine opening, told the Los Angeles Times that the workers had previously complained about a gas leak in the mine. Norma Vitela, the wife of a mine worker trapped inside the mine, told The Miami Herald that her husband complained about the same leak.
By February 21, 2006 Grupo México search teams and relatives of the trapped miners were beginning to lose hope. Each miner was allotted an oxygen pack, but the pack only guaranteed the miners six hours of oxygen. The Governor of Coahuila, Humberto Moreira Valdés, told the Televisa television network that the mine's ventilation service, which uses fans to import oxygen and export dangerous gases, was still in operation. However, the February 21 edition of The Miami Herald remarked, "Even so, they could not be certain the precious oxygen was arriving to where the miners were trapped."
On February 23, 2006 Grupo México advanced to a part of the mine shaft where they believed two of the 65 workers were trapped. However, they found nobody, leading them to believe the force of the explosion knocked them through the mine shaft deeper than they had anticipated. The next day, Grupo México advanced approximately halfway into the 1.75-mile long mine, where an additional twenty-four miners were expected to have been found. Again, nobody was found, and Grupo México hypothesized that either the miners were buried under debris or the miners were located in a deeper part of the mine. On the evening of February 24, Grupo México announced that search efforts were to be suspended for two or three days, due to the search teams advancing to a portion of the mine which leaked out high levels of natural gas. On the afternoon of February 25 the CEO of Grupo México confirmed during a press conference that "there was no possibility of survival after the methane explosion", based on a scientific report. The following day the Secretary of Labor, Francisco Javier Salazar Sáenz, and Governor Moreira announced the mine would be closed indefinitely once all the bodies were recovered.
The Diario newspaper of Ciudad Juárez published a report from Mexican officials and the U.S. Mine Safety and Health Administration, stating that due to the high levels of gas in the mine, it would be very rare, if not impossible, to have any survivors from the rescue efforts. Diario also published reports from mine workers that they had gone on strike against Grupo México at least 14 times, "not only for salary increases… but because of its constant refusal to review security and health measures." Grupo México said that they, in conjunction with the mining union, signed a certificate on February 7, 2006 declaring the mine safe.